1. Field of the Invention
This invention relates to an automatic lead frame feeding device for a TO-200 semiconductor manufacturing apparatus, which automatically feeds lead frames to die bonding and wire bonding processes for manufacturing TO-220 semiconductor packages.
2. Description of the Prior Art
Generally, a semiconductor package is classified into a hole insertion packaging type and a surface packaging type according to a packaging form, and the hole insertion packaging type is further classified into a lead frame type and a pin type. This invention resides in a device for sequentially feeding lead frames during manufacturing of semiconductors of a single inline package type (will be hereinafter referred to as "TO-220 semiconductors") in the lead frame type.
This TO-220 semiconductor has an adverse effect on the semiconductor element resulting from heat generation during operation of the element. Therefore, a heat sink having a radiating surface of a great area and serving as a radiating path has been necessarily provided to be exposed to a top of a casing of the semiconductor element, thereby preventing breakage of the element due to elevation of an internal temperature thereof.
A lead frame having such a radiating path is of the form as shown in FIG. 1 of the accompanying drawings and comprises the heat sink 1a serving as the radiating path, a paddle 1b formed integrally with the heat sink 1a for attaching thereto a chip, a plurality of outer lead portions 1c connected integrally to the paddle 1b through respective bent portion 1f extending at a given angle from the paddle, and a support portion 1d for reinforcing and supporting the outer lead portions 1c. Further, there are formed index holes 1e in the heat sink 1a and the support portion 1d.
During the manufacture of the TO-220 semiconductor packages by using the thus constructed lead frames, the following principal processes are performed: a die bonding process for bonding the chips obtained in a dicing process to the paddles of the lead frames; a wire bonding process for interconnecting the chips and the lead frames by wires; a molding process for hermetically sealing the chips with resin; and a lead shaping process are performed, thereby producing a plurality of the complete semiconductor packages each being of the form as shown in FIG. 2. At this time, to perform the die bonding and wire bonding operations, the lead frames 1 must be loaded in a loader of the semiconductor manufacturing apparatus.
In the past, since the lead frames 1 were slopingly stacked in the loader of the semiconductor manufacturing apparatus owing to the bent portions 1f between the paddle 1b and the outer lead portions 1c, the lead frames could not be introduced directly into the loader, but instead were manually put into a separate magazine (not shown) at equal distances and in the same direction by an operator, and then introduced into the loader along with the magazine containing them. At this time, one magazine can contain about 20 sheets of the lead frames.
When the magazine containing about 20 sheets of the lead frames has been introduced into the loader, the lead frames are fed one by one to the die bonding or wire bonding process by an air cylinder actuated lower plate as the magazine is lowered stepwise by a stepping motor.
This automatic lead frame feeding device of the prior art is however disadvantageous in that the manual putting of the bent lead frames into the separate magazine is a tedious and time-consuming task and the replacement of the magazine is also a complicated task, resulting in lowering of productivity. Further, when the magazine is lowered stepwise by the stepping motor to feed the lead frames, index points may be out of register with each other, and thus jamming may occur.